A railroad vehicle is equipped with brake cylinders each of which is connected to brake rigging through which mechanical force is applied to and released from the brakes of the railroad vehicle. The brake cylinder is an apparatus through which pneumatic pressure is converted to the mechanical force. By supplying to and removing from the brake cylinder pneumatic pressure, the brake cylinder supplies to and releases from the brake rigging the mechanical force necessary to apply and to release, respectively, the brakes of the railroad vehicle.
A typical brake cylinder includes a brake cylinder body, a head casing, a piston and rod assembly, a push rod assembly, and a typical push rod holder. The brake cylinder body includes a bolting flange and defines a first bore that extends from the bolting flange to a piston head seat. The brake cylinder body also defines an inlet port in communication with the first bore. The inlet port is connectable to a source of pressurized air. The head casing also includes a bolting flange and defines a second bore extending therefrom to a seal seat circumscribing an open bore therein. The bolting flanges bolt together so as to form an enclosure encompassing the first and second bores.
Housed compressively within the enclosure, the piston and rod assembly includes a hollow piston rod, a second spring seat, a sealing member, and a release spring. The hollow piston rod has at a closed end a diaphragm piston head and defines at an open end at least one set screw hole and a first pair of aligned holder pin throughholes. Each set screw hole and holder pin throughhole is oriented perpendicularly to a longitudinal axis of the hollow piston rod. The diaphragm piston head is slidable within the first bore. The hollow piston rod less the diaphragm piston head is slidable within and extendable from the open bore. On a back side, the diaphragm piston head has an annular surface formed to a first spring seat. The second spring seat is concentrically disposed about the hollow piston rod and permits the hollow piston rod to slide therein. The sealing member is disposed between the second spring seat and the seal seat of the head casing and permits the hollow piston rod to slide therein. The release spring is concentrically disposed about the hollow piston rod between the first and second spring seats and compressed within the enclosure. The diaphragm piston head is thus forced against the piston head seat of the brake cylinder body while the sealing member via the second spring seat is likewise forced against the seal seat of the head casing.
The push rod assembly has a socket end and a coupler end, the latter of which defining a locking holder pin throughhole. The socket end inserts within the hollow piston rod via its open end. The coupler end couples to the brake rigging.
The typical push rod holder is a metal ring. The typical push rod holder defines at least one set screw throughhole and a second pair of aligned holder pin throughholes. Each of these throughholes is oriented perpendicularly to a longitudinal axis of the typical push rod holder. The typical push rod holder is concentrically disposed about the hollow piston rod and the push rod assembly contained therein. At least one set screw inserts through the at least one set screw throughhole of the typical push rod holder and fastens into the at least one set screw hole of the hollow piston rod. This serves to attach the typical push rod holder to the hollow piston rod. A holder pin device inserts through the holder pin throughholes of the typical push rod holder, the hollow piston rod and the push rod assembly therein. This serves to connect the hollow piston rod and push rod assembly contained therein within the typical push rod holder.
When less than a predetermined pressure is fed into the inlet port, the typical brake cylinder sets in a release position. In the release position, the diaphragm piston head remains situated forcibly against the piston head seat of the brake cylinder body and the hollow piston rod with the push rod assembly therein remain predominately retracted within the enclosure. No force is transmitted to the brake rigging. When more than a prespecified pressure is fed into the inlet port, the typical brake cylinder sets in an applied position. In the applied position, air pressure forces the diaphragm piston head to move away from the piston head seat. This further compresses the release spring. The hollow piston rod with the push rod assembly therein extends from the enclosure thereby transmitting force to the brake rigging through the push rod assembly.
The typical brake cylinder is designed so that there is a gap between the typical push rod holder and the hollow piston rod to which it is concentrically attached. During operation of a train, the typical brake cylinders experience substantial vibration as the railroad vehicles move along the railroad tracks. In particular, the typical brake cylinder encounters vibrations at a junction where the typical push rod holder connects about the hollow piston rod and the push rod assembly therein.
Experience has shown that these vibrations damage these components. Specifically, the gap between the typical push rod holder and the hollow piston rod permits relative motion between these components. During vibration testing as illustrated in FIGS. 7 and 8 and in actual use, these vibrations have been shown to strain and wear the set screws and the holder pin unduly. These vibrations also elongate both the set screw holes in the hollow piston rod and the holder pin throughholes in the hollow piston rod, the push rod assembly and the typical push rod holder. Metal particulates or shavings have abraded from these components as a result of these vibrations. After a certain degree of wear, these components must be replaced and to do so requires a complete overhaul of the typical brake cylinder. Though this wear occurs over some period of time, it nevertheless reduces the operational life of the typical brake cylinder.
The present invention is primarily intended to address such shortcomings in the typical brake cylinder. Unlike prior art push rod holders, the instant push rod holder absorbs forces caused by vibration of the aforementioned components. Wear to the aforementioned components is minimized and brake cylinders so equipped require maintenance much less often. The instant push rod holder thus reduces likelihood of damage to, and prolonging operational life of, the brake cylinder.
It should be noted that the foregoing background information is provided to assist the reader in understanding the present push rod holder invention and any terms used herein are not intended to be limited to any specific meaning unless specifically stated otherwise in this specification including the following detailed description.